Abstract

The nascent stages of speciation start with the emergence of sexual isolation. Understanding how reproductive barriers influence this evolutionary process is an ongoing effort. We present here a study of Drosophila melanogaster populations from the southeast United States and Caribbean islands undergoing incipient sexual isolation. The existence of premating reproductive barriers have been previously established, but they do not fully account for the degree of isolation present. To assess the influence of postmating barriers, we investigated putative postmating barriers of female remating and egg laying behavior, as well as hatchability of eggs laid and female longevity after mating. While we did not find any effects in female remating or egg laying, we did observe lower hatchability in the central region of our geographical spread as well as shorten female life spans after mating to genetically different males in females originating from the northern- and southernmost locations of those surveyed. These results serve as evidence that long-term consequences after mating such as the fitness of offspring and shortened lifespan have a stronger effect than short-term postmating behaviors.

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